On 21st of May 2016 UWE-3 celebrated 2.5 years in space without any significant failures. Batteries, EPS, OBC and ADCS are fine, nevertheless we were confronted with a minor problem with one of the radios UWE-3 autonomously recovered from. Since then UWE-3 is in a very stable condition again.

Some weeks ago we have re-initiated operations with UWE-3 on an interim basis. The goal is to test new magnetic control algorithms in space. Therefore we operate the satellite on the 436.395200 MHz frequency and perform data downloads from time to time. In the figure below the satellite’s rotation rate w is shown for one of the experiments. The goal was to establish a rotation about the satellite’s X-axis (blue) at 10 deg/s while the Y/Z-axes should be at 0 deg/s. In general the desired rotation rate could be achieved but with major deviations from the setpoint. With the intention of optimizing the relevant control laws we will continue with these experiments within the next days and weeks.

During our experiments we received an outstanding support from the radio community from all over the world we are very thankful for. The received packets were instantaneous injected into our algorithms and delivered an important contribution to our research work. We would like to express our special thanks to DK3WN, PE0SAT, DL8MCO, EU1XX, ON4HF, Rainer, JA5BLZ, JA6PL, CU2JX, LU4EOU, JA1GDE, SP7THR, G7GQW, YC3BVG, JF1EUY, JE9PEL, JE1CVL, JO1PTD, ZL4JL, EA7ADI, K4KDR, JA0CAW, JH4XSY, PA2EON, SM0TGU. THANK YOU!

The GRIFEX operations team just wanted to give you a quick update on operations and thank you for your continued support of the mission.

First off, we’ve now had 30 successful MARINA run completions at various locations across the US and Canada. Many of these images have unfortunately been saturated, but we did downlink a few images with interesting features. We are still waiting on confirmation from JPL of a good image before we release these images, but it appears as though the most interesting ones come from mid-latitudes in the continental US (Arizona or Virginia latitudes).

In addition to MARINA data, we’ve also been downlinking telemetry to ensure the continued health of the satellite, as per usual.

On the Ann Arbor passes during which we are not downlinking, we’ve been experimenting with the magnetorquers on GRIFEX. GRIFEX has three coils of wires, each aligned with one axis of the spacecraft (X, Y, or Z). When we run current through these wires, a magnetic dipole is generated that interacts with Earth’s magnetic field to alter GRIFEX’s attitude. Thus far, we have just been “pulsing” the coils, i.e. running current through them for only 10 seconds at a time, to make sure they are functioning properly and that the magnetometers record an appropriate change in magnetic field. You can see the results of our experiments in the three graphs below:

You’ll note that the X and Y coils draw much less current than the Z coil does and generate a much weaker change in magnetic field – this is because the Z coil needs to be strong enough to overcome the permanent magnet on GRIFEX (which is aligned with the Z axis of the spacecraft) if necessary. Thus far, we have only experimented with running current in one direction through the magnetorquer coils, but we plan on completing “pulse” tests with current running the opposite direction before we attempt full attitude control of the spacecraft.

Another event to note is that GRIFEX stopped beaconing sometime between 7/30/2015 23:45:00 UTC and 7/31/2015 00:51:00 UTC. At the 00:51:00 UTC pass over Ann Arbor, we attempted to reset the spacecraft, but to no avail; GRIFEX was neither beaconing nor responding to any commands we sent. GRIFEX remained silent throughout 7/31/2015, but luckily a watchdog timeout reset the spacecraft and we started picking up beacons again on 8/1/2015 13:55:00 UTC. We are still unsure of what caused this anomalous behavior, but we have been downlinking telemetry from the time period during which GRIFEX was silent (beacons were still being created and saved on the spacecraft) to debug the problem and ensure it does not happen again. A big shout out to the hams that were tracking GRIFEX during this worrisome time and alerting us to the fact that it was silent! We are all very glad that the GRIFEX mission can continue now that the spacecraft is beaconing again.

It has not yet been recovered. The command team turned the transmitter on to test it out on June 28th, but they still need to upload the secondary boot-loader and then the high level code necessary to operate the satellite. The issue in the past has been that the satellite crashes when they try to run high level code. We will see if they’ve managed to work around that problem (probably radiation damage to a section of the satellite’s memory).

Please do not transmit unless you hear the FM repeater functioning. Any interference while the command team is attempting to upload new code will significantly prolong the recovery process.

Source: N8HM (07-07-2015 12:48 UTC)

After I had read the news on the Amsat-BB about AO-27 being active again, I visited the AO-27 website and found the following information.

June 28, 2015:
AO-27 Turned on today. Seems good on the bootloader. If anyone has contacts into CelesTrak to get AO-27 back into the amateur.txt file it would help some of the control operators stations. Our e-mails have gone unanswered.

Michael, N3UC

Dan, KM4HZJ

James, N3UCC

April 18, 2015:
AO-27 Turned on today. Uploaded Secondary boot loader

Michael, N3UC

April 12, 2015:
Turned on High power to check power output. Looks good.

Michael, N3UC

Lets listen for the satellite, decode some telemetry and pass it on to the operators so they have a clear idea about the health of AO-27 (EYESAT-1). Don’t transmit unless you hear the FM repeater functioning.

After the communication anomaly and the autonomous recovery of UWE-3 two weeks ago we uploaded an extended software to the OBC to analyze the event in detail. As we already have known the EPS, OBC and ADCS were not affected, so the secondary radio.

During the tests made possible by the new software we temporarily switched back to the primary radio to check its electrical characteristics and communication performance. As the values were promisingly normal we performed extensive communication tests without seeing any existing anomaly. Therefore we will continue normal operation.

Our primary challenge in the past couple of weeks has been cold temperatures aboard the satellite. You may have noticed increased beacon frequency and higher transmit power – this was to keep the battery above the 0 deg. C minimum safe charge temperature.

We have completed several more MARINA runs with differing features, however, we are waiting on confirmation from JPL of a good image before we can release any images. Additionally, we have been able to pinpoint increased voltage drops during beacon transmissions as one source of MARINA aborts, so we have applied the appropriate mitigations (no beacons during MARINA runs) in order to reduce the overall number of aborts.